1. Field of Invention
The present invention relates to a device for holding goods in logistics transportation, in particular, to a force measuring ratchet tie down.
2. Related Art
Goods usually need be fixed during transportation by vehicles to make the delivery safe and reliable. It is not only of low efficiency but also laborious to bind the goods with conventional nylon ropes or wire ropes. Also, the goods could hardly be bound tight. The goods could be bound and positioned expediently by using a tie down which is widely used nowadays and very popular amongst the workers in the field of logistics transportation.
The tie down currently used for logistics transportation includes a body, a handle, a ratchet, a scroll, a catch, a teeth stop board, a mesh belt, a belt hook and a spring. The tie down has a two belt hooks, in particular, a positioning belt hook and a mobile belt hook. The positioning belt hook is fixedly connected with the outer end of the positioning belt. The inner end of the positioning belt is fixedly connected to the body. The mobile belt hook is fixedly connected with the outer end of the mobile belt. The inner end of the mobile belt is rolled on the scroll. The mobile belt could be elongated or shortened for binding as the scroll rotates. In particular, the roll of the mobile belt is accomplished as follows. The handle is pulled and the lateral plate of the handle could be brought to rotate around the scroll. The catch on the lateral plate makes the ratchet rotate in a single way, so that the mobile belt could be rolled gradually because the ratchet is fixedly connected to the scroll. The extension of the mobile belt could be acquired in the following. The hand is pulled to detach from the ratchet. The mobile belt brings the scroll to rotate in a reverse direction by tension, so that the mobile belt is rapidly loosened.
For example, Chinese Patent Application No. 200610028900.2 discloses a tie down of an adjustable belt loosening speed, which has a body and a handle. A positioning belt is fixed at the end of the body. A positioning belt hook is placed at the outer end of the positioning belt. The side plate of the body is hinged to the side plate of the handle via a scroll. Each one of both ends of the scroll has a ratchet covered thereon. A mobile belt is rolled on the scroll. A mobile belt hook is positioned at the outer end of the mobile belt. The body is movably connected with a teeth stop board which could be matched with the ratchet. The handle is movably connected with a catch which could be matched with the ratchet. A dent matched with the ratchet is provided on the side plate of the body. An inclined face is set on the side plate of the handle. When the end of the catch is placed within the dent, the teeth stop board is positioned at the upper part of the inclined face to detach the teeth stop bard from the teeth of the ratchet.
However, the condition of the tensioning force of the binding belt could not be understood during use of the tie down. Thus, it is difficult to control the tie down, causing the goods to be damaged or the binding belt to be broken for the goods are bound over-tight. Or, the transportation of goods is adversely affected for they are not bound sufficiently tight. Furthermore, the forces used to bind different kinds of goods or same goods at different positions are different when the goods are to be bound, which aggravates the difficulty in control. On the other hand, the tensioning force of the binding belt of the tie down could be varied due to dumping or shaking during transportation. In this case, the tensioning force of the binding belt is over-large at some sites and too small at some other sites. Therefore, it is required to adjust the tensioning force, which could not be achieved by the current tie downs because the tensioning force of the binding belt could not be understood and thus difficult to be conditioned.